In the body and/or frame of every motor vehicle such as a car there are important control points or measuring points for various components the relative positions of which are exactly specified by the car manufacturer and established when the car is manufactured. Normally, for safe operation of the car, it is important that this orientation of various parts be maintained and that the correct orientation be re-established after damage has occurred to the car. After body work repairs have been carried out and also whenever there is reason to suspect that deformation has occurred after an accident, even a slight one, the position of the measurement points should be checked and, if necessary, corrected.
A known arrangement for checking and straightening vehicle bodies has a set-up bench in the form of a strong steel frame over which the vehicle to be examined is suspended with the aid of so-called body work clamps which are releasably locked to the sides of the bench and engage and support the body and/or frame of the vehicle at appropriate points. The bench is equipped with an accurately machined reference surface, preferably on the upper face of the bench, and on this surface a measuring rail system or a so-called measuring bridge is received. The measuring bridge has accurately parallel rails, transverse slides, and probes all equipped with scales. With the aid of this bridge points on the body or frame can be mesured along three orthogonal reference axes at right angles to each other which coincide with the longitudinal direction (x), transverse direction (y) and vertical direction (z) of the body and frame. The rails of the measuring bridge are first positioned relative to the body being examined, after which, by means of the slides, probes and scales, the location of the vehicle control points can be checked and measured. With the aid of the scales on the measuring bridge the spatial position of the measuring or control points can be determined. After comparison with the data from the manufacturer, it can be determined whether they are in the correct position or not.
These systems have drawbacks, however, in that it is often inconvenient, time consuming and difficult for the operator to accurately read the measurements registered on the scales, because the space available for this end is often relatively confined or restricted by the vehicle body and bench and because the operator has to bend and stoop forward towards the bridge, in order to take a reading. In addition to being physically difficult to use, these systems often result in inaccurate readings by the operator, because some of the scales are at right angles to each other, making it extremely difficult and often impossible for an operator to utilize a single sighting line at substantially a right angle to these scales for reading them which is necessary for accurate measurements.